1. Field of the Invention
The present invention relates to a method, apparatus and material for forming packages and more particularly to a method, apparatus and material for continuously forming packages from strip packaging film by passing the film over a forming shoe.
2. Prior Art
Devices are presently used which form packages from strip packaging film and at the same time fill the packages with product. For example, U.S. Pat. No. 2,899,875 discloses a method and apparatus in which a strip of packaging film is drawn over a forming shoe which shapes the film into a tube in which the edges of the film overlap to form a seam. Both edges of the film are coated with a heat sealing compound and are joined as the seam of the tube is drawn between a heated shoe and a tongue.
In later versions of this apparatus, one side of the film (which is to become the inner surface of the package) is completely coated with a hot melt coating which also serves as a package liner to protect the contents from moisture. This improvement facilitates the joining of the edges of the film to form the longitudinal seam and permits the tube itself to be laterally sealed at spaced intervals by the coaction of a pair of heated dies.
However, these later versions possess a disadvantage in that the hot melt coating on the film accumulates on the tongue during successive seam sealing operations resulting in lumpy seams and frequent shut downs of the apparatus to clean the tongue.
Accordingly, the need exists for a system which avoids the problems of coating accumulation on the tongue and yet provides the advantages of the completely coated films presently in use.